ETHANOL STIMULATES PHOSPHOLIPID TURNOVER AND INOSITOL 1,4,5-TRISPHOSPHATE PRODUCTION IN CHLAMYDOMONAS-EUGAMETOS GAMETES

Alcohols induce mating-structure activation in Chlamydomonas eugametos gametes. From the effect of ethanol on the P-32-labelling of polyphosphoinositides, we conclude that the synthesis of these lipids is stimulated. Biologically inactive concentrations of ethanol (< 6%) had no effect on synthesis, but 6-8% ethanol stimulated synthesis for upto 60 min. The P-32 incorporated into polyphosphoinositides and phosphatidic acid during ethanol treatment was readily chased out when 1 mM unlabelled Na3PO4 was added. Using a binding assay for inositol 1,4,5-trisphosphate, we show that the production of this phospholipid constituent is dramatically increased after ethanol treatment. This effect, coupled to a rise in intracellular calcium concentration, could explain gamete activation. The significance of these results in explaining other ethanol-induced phenomena in algae is discussed.